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Table 4 Several conserved sequence motifs in TMTCs are related to DPM binding and divalent metal ion coordination

From: Conserved sequence motifs in human TMTC1, TMTC2, TMTC3, and TMTC4, new O-mannosyltransferases from the GT-C/PMT clan, are rationalized as ligand binding sites

Motif Residues TMTC1 TMTC2 TMTC3 TMTC4
M1 (red)
DD in EL1
D 52 26 31 45
D 53 27 32 46
M2 (orange)
SHKSYRP in EL1
mannose
S 88A 61C 66B 80A
H 89A 62B 67A 81A
K 90B 63C 68A 82A
S 91A 64A 69B 83A
Y 92C 65 70B 84B
R 93C 66 71 85A
P 94 67 72 86A
M3 (yellow)
RxD in EL2
R 167 139A 143 172C
D 169 141A 145B 174
M4 (green)
KE(T/Q) xxT in EL3
K 219A 186A 188A 221A
E 220A 187A 189A 222A
T/Q 221(T)A 188(Q)A 190(Q)A 223(Q)A
T 224A 191B 193B 226C
M5 (blue)
DW in EL4
D 330A 293A 303A 338A
W 331 294A 304A 339A
M6 (violet)
PxxP in TM9
P 386A 404C 358A 394C
P 389B 407A 361A 397B
M7 (pink)
ERxxY in EL5
E 403A 421A 375A 411
R 404C 422A 376C 412
Y 407C 425C 379 415B
  1. Conserved residues present in the vicinity of the ligand dolichyl-phosphate-mannose (DPM) are part of seven motifs M1-M7 in the TMTC family protein sequences. For each motif, the actual sequence, the location (loop number or TM number), loop coloring in Fig. 4 and the residue numbers in TMTC1/2/3/4 respectively are listed. If at least one atom of the residue is within 5 Å, 6 Å or 7 Å of any atom of DPM, the respective residue is marked with the corresponding subscript “A”, “B” or “C”. In bold, we indicate residues in M4 and M5 observed for coordinating the divalent metal ions. We find motifs M2 and M3 largely involved in mannose interactions, M6 provides for the dolichyl tail, and M4, M5 and M7 are important for interaction with the phosphate